The world is mounting a massive relief effort to respond to the escalating death toll from the tidal waves that raced across the Indian Ocean Sunday, triggered by one of the most powerful earthquakes ever recorded. In just the past 24 hours, the death toll from the devastation across a dozen or so countries from Thailand to Somalia has more than doubled, with the number now believed to top 50 thousand. Millions more have been left homeless as a result of what is now being described as one of the worst natural disasters in recent history.

Three days after the magnitude nine earthquake struck deep undersea off the western tip of Indonesia, the death toll continues to climb and governments in the region are warning the total number of dead is still far from being known. Those who survived are recalling the shock of how some of South East Asia's most popular beach resorts were devastated in an instant by a mountain of water that no one, it seemed, knew in advance was about to crash ashore.

TOURIST #1: "Suddenly, everybody stopped. You could see a big surf coming in and then it just hit and there was devastation, boats getting smashed everywhere, people being washed away, just carnage really."

TOURIST #2: "Everything was under water, there were people running and screaming, nobody knew what was going on."

There are fears that entire coastal and small island communities may have been washed out to sea in some remote areas closest to where the quake struck.

“A number of people got swept away by the tidal wave,” said Indian National Security Advisor J.N. Dixit.

And, Patrick Nicholson of the Catholic Agency for Overseas Development suspects the worst for inhabitants of islands off the tip of Sumatra, close to the epicenter of Sunday's powerful quake.

"Government reports say the population there, 76,000 ...planes, spotter planes went to the area and they saw no people whatsoever on the islands, badly destroyed," he said.

Indonesia and Sri Lanka are hardest hit. Ashish Josi of Sky Television made it to the devastated Sri Lankan city of Galle.

"We drove through small villages on our way into Galle today and everywhere we looked there were dead bodies,” he added. “And driving into Galle, we were mobbed by scores of people. They are desperate for food, water, medicine, clothing, anything they can get their hands on. And there is a desperate shortage of fuel, of all the basic necessities you need and that's going to get worse over the next couple of days."

In fact, the World Health Organization (WHO) is now warning that if aid does not get to areas where it's needed quickly, outbreaks of cholera and malaria could claim as many lives as the initial earthquake and tsunami. United Nations Undersecretary General for Humanitarian Affairs Jan Egeland says the world body may be in the verge of issuing its largest appeal for assistance ever.

"I think this is unprecedented because very many countries are involved,” he noted. “However, some of the countries are coping themselves very well which means that we can concentrate on four or five of the about 10 countries affected."

Governments, including the United States, are mobilizing to help. Washington has pledged $35 million in relief aid as well as military transport planes to help fly in supplies. Secretary of State Colin Powell expects that figure could change as the full extent of the tragedy becomes known.

"We will do more but we're still getting an assessment of what is needed and it will take time for that assessment to be made to see what nations can do for themselves, to see what the specific needs are and then we'll respond to those needs," he said.

In the aftermath of the disaster, questions are now being raised about whether lives could have been saved if the region had a tsunami warning system in place. Although seismologists in Hawaii detected the quake, governments in countries bordering the Indian Ocean do not have an early warning system, like Pacific Ocean nations do, for alerting one another about the threat of tsunamis that earthquakes of this magnitude can generate.